Rats named after ‘Doom’ creators are playing ‘Doom’

"At this point the rat should be thirsty for some kills"

A neuroscientist has trained lab rats to play a custom version of classic id Software shooter Doom – and named them after three of the original game’s key creators: John Romero, John Carmack, and Tom Hall.

In his original experiment, neuroengineer Viktor Tóth writes that he set out to “train rodents to play Doom II with full cerebral control”. This involved teaching “rats or mice to kill demons and find the exit point by decoding their motor intent and translating it into in-game actions”. Now, a year later, he’s succeeded in “training rats to kinda play Doom (as spotted by PCGamer).

To do so, Tóth built a custom “VR for rats” rig, that placed one of the three rats – Romero, Carmack, or Tom – on a large makeshift trackball in front of a curved monitor that would fill the rat’s field of view. While their body was held in place by a robot arm, the rat would be free to ‘walk’ across the ball. Movement and action were incentivised by providing the rats with sugar water, provided by tubes.


Tóth used a custom build of the game that initially only presented the rats with straight corridors with simple turns, before introducing more complicated routes that included dead ends and random turns, building up to having the ‘players’ navigating the full Entryway map from Doom II.

Teaching rats to shoot was more complex, with Tóth considering a method that would track the rats’ bite action – as the positioning of the game’s shotgun would line up with a rat’s physical orientation, roughly in line with its nose, a bite could have tracked well. Ultimately though, a rearing motion was decided upon, requiring greater intent on the rats’ part.

The build would start by placing Imps in the rats’ way, needing to be shot before allowing them to proceed. “At this stage, the Imps can’t move or attack,” Tóth writes. When a rat successfully dispatched its enemy, “extra, juicy rewards shall follow the death of demons.”

Eventually, moving enemies were introduced, but fear not, because “at this point, the rat should be thirsty for some kills.”

For anyone concerned that Tóth may just be training up an army of killer rats to take over the world, relax – the research has more benign applications. Electrodes could record the rats’ motor intentions, while mapping them to their actions, which could lead to progressions in prosthetics or human-computer interfaces, in turn improving life for people with physical impairments.


Tóth has been working on teaching rats how to play Doom for a year now, and both the original research and the latest developments make for fascinating – if technical – reading, and could lead to major developments in future.

In other news, Sega’s 4X strategy game Humankind is already benefitting from a keen modding community, shortly after the release of dedicated modding tools. Players have already created maps based on the likes of World of Warcraft’s Azeroth and The Elder Scrolls’ Tamriel.